Furnace regulation



"April 27 1926.

*s. H. GIBSON FURNACE REGUHATION Original Filed ay 25. 1918 I mvmma v ATTORNEY Patented UNITED STATES PATENT OFFICE.

cnoaen H. GIBSON,-OF orrnn MoNrcLAm, nnwannsnr.

summon REGULATION.

Original application filed May 25, 1918, Serial No. 236,450. Divided and this application filed June 20, 1925. Serial No. 38,446.

To all whom it may concern:

Be it known that I, GEORGE H. GiBsoN, a citizen of the United States, and resident of Upper Montclair, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Furnace Regulation, of which the following is a specification. y

The general object of the present invention is to provide improved regulating means especially. adapted for, though not necessarily limited to use in controlling combustion in furnaces such as steam generating boiler furnaces, and particularly for automatically proportioning. the amounts of air supplied .to such a. furnace to support combustion therein While maintaining a predetermined pressure condition in the com bustion chamber of the furnace. More specifically, the object of theinvention is to combine with a damper or like flow regulating device, provisions for maintaining a.

substantially constant differential pressure at opposite sides of the damper whereby the adjustment of the latter into different po- 'sitions produces definite corresponding variations in the rate of flow ast the damper.

The various features of novelty which characterize my invention are pointed out with artieularity in the claims annexed to and orming a part of this specification. For a better understanding of the invention, however, its advantages and specific objects attained with its use, reference should-be had to the accompanying drawings and descriptive matter in which I have diagrammatically illustrated and described a preferred form of embodiment of my invention.

Of the drawings: iz-Fig. 1 i s a somewhat diagrammatic representation, with parts broken. away and in section, of a steam generating boiler furnace and combustion control apparatus associated therewith;

.Fig. 2 is a partial section taken on the line 2-2 of Fig. 1; g

Fig. 3 is a partial section line 3-3 of Fig. 1; and

Fig. 4 is a partial section on the line 4-4 of Fig. 1. V In the drawings, A represents a conventionally illustrated steam generating boiler furnace of the return tubular type, in which taken on the immediately back of A'is the ash pit, A, the portion of the 001m bustion chamber above the fuel bed separating this chamber from the ash pit beneath it, and A, the portion of the combustion chamber lying beyond the bridge wall B. The throat or passageway above the bridge wall connectin the combustion chambers A and A is divi ed up into a plurality of tortuous passages by vertical posts O and C of refractory material, shown in the form of posts or columns arranged in two staggered rows. The secondary air for burning the combustible gases rising from the fuel bed, is supplied to the furnace through a conduit or channel B in the bridge wall, and receiving air through a supply conduit B The conduit B discharges air into the throat con necting chambers A and A, through a plurality of discharge ports or tuyeres B As shown, each port B opens at its upper end a corresponding post C. e primary air for combustion is supplied tothe ash pit A through the discharge conduit D of a fan or blower D, operated by a steam motor D The latter is supplied with the necessary steam motive fluid through a'branch pipe D connected to the steam pipe E of the boiler. The supply of steam through the pipe D to the motor D is controlled by a throttle valve F, having its operating stem connected to the diaphragm of a fluid pressure device G. This diaphragm has one side exposed to the pressure of the atmosphere and the other. side exposed to the steam pressure transmitted from the steam pipe E through the branch pipe G. The pressure of the atmosphere is on the diaphragm supplemented by the action of a spring G The purpose of the device G and the valve F controlled by it is to so vary the amount of primary air supplied to the furnace as to maintain a constant steam pressure in the boiler.

The stack draft to which the furnace is subjected is controlled by a damper H located in the stack connection A". The stack damper H is connected to a piston R workpressure transmitting ipes P. and P to the cylinder S of a contro mg valve. The valve member S, working in the cylinder S, as shown, is balanced and-is connactodby an arm T to the diaphragm T of a pressure motor T, the chamber in which is connected to the interior of the combustion chamber by a pressure pipe P As shown, the pressure ipe P opens to the combustion space of the iurnace in the passage connecting the chambers A and A A pressure motive fluid, as compremed air, is supplied to the cylinder S through the supply conduits}. The arm T passes through a slot S in the side wall of the cylinder S,serving not only as av passage for the arm Tfi'but also as an exhaust port. An adjustable loading rspring T is connected to the arm T so as to impart a slight pull to the left on the diaphragm T.

In consequence the pressure in the chamber.

' of the motor T will normally be slightly be-' low that of the atmosphere.

The valve member S proper is so formed that when the pressure in the pressure chamber of the motor '1' falls below the desired pressure and the diaphragm -T, through the arm T", thereupon moves the piston S to the right from the position shown in Fig. 1, the pressure fluid supplied by the pipe S will pass through the pipe 1? into the left hand end of the cylinder R, while .at the same time the right hand end of the cylinder It will be connected through the pipe P and to the peripheral channel in the valve member 'S to the exhaust port S This will move the piston R to the right and thereby throttle the stack draft and increase the pressure in the combustion chamber. Similarly, when the pressure in the combustion chamber rises above the desired value the dia phragm T will displace the valve member S to the left, thereby connecting the right hand end of the cylinder R to the cylinder i ml S, and the left hand end of the cylinder R to exhaust. This will cause the damper H to open and thereby restore the desired pressure in the combustion chamber.

- The passage of secondary air into the channel B, through the passage B is regulated by a sliding throttle valve U con nected to a piston U, working in a cylinder U. The right hand end of the cylinder U is connected by a pressure pipe P to a Pitot tube Q, located in the primary air supply conduit D, and the static pressure in the conduit D is transmitted to the left hand end of the cylinder U by the pipe P A spring U exerts a slight loading force onthe piston U, tending to move it to the right. With the arrangement described, an increase or decrease in the rate of flow, through the conduit D, produces a corresponding opening or closing movement of the Valve or damper U As shown, the portion of the conduit B adjacent the level of the damper U is so shaped that slight movements of the damper will produce greater differences in throttling efiect when the volume of flow through the conduit D reeaeee is small, than when large. Preferably, as shown, the cross section of the conduit- B is such that the free area past the damper U in the conduit B will be proportional to the square root of the difference between the pressures transmitted to the two ends of the cylinder U.

lVith the apparatus shown in Fig. l, the amount of primary air supplied is dependout upon the steam pressure, and the pressure in the combustion chamber of the furnace will be maintained constant and slightly below that of the atmosphere, while the amount of secondary air supplied will depend upon the free area of How through the conduit B past the damper U, and this area will be proportional to the volume of flow through the conduit D, so that the ratio of primary and secondary air supplied is kept constant, while at the same time the pressurein the combustion chamber is also maintained constant. I A characteristic feature of the invention herein claimed is that damper H by main-v taining a constant combustion chamber pressure, maintainsa constant pressure dii ierential; namely, the difference between the pressure of the atmosphere at the lower end of the conduit B and the constant combustion chamber pressure in the conduit B at the opposite sldes of the control damper U In consequence, the rate of flow past the damper U for any given adjustment of the latter will be definite, and can-be p:edc-

termine d. Novel features of the furnace regulation system disclosed but not claimed herein are claimed in my prior application,

Serial No. 236,450, filed May 25, 1918, of whichthis application is a division.

While in accordance with the provisions of the statutes I have illustrated the best form of embodiment'of my invention now known to me, it will be apparent to those skilled in the art that changes may be made in the form of the apparatus disclosed with out departing from the spirit of my invention as set forth in the appended claims and that in some cases certain features of my invention may be used to advantage without a corresponding use of other features.

Having now described my invention, what I claim as new and'desire to secure by Let ters Patent, is:

LA combustion controlling system com prising a combustion chamber, a passage way for the air and gases through and meluding said chamber, a damper in said passageway regulating the flow of air to the combustion chamber, and means for maintaining a substantially constant differential in pressure at the damper whereby the quantity of air flowing past the damper is in direct proportion to the damper opening alone.

2. The method of regulating furnaces in the passa eway for the gas and in main which consists in controlling a constriction 1n the passageway for the air and gases through the furnaceand in maintaining a substantially constant differential in pressure taining a su bstantially constant differential in pressure at the point of constriction.

5. The method of regulating the flow of gas under pressure through a passageway which consists in regulating the flow of gas by varying a constriction in the passageway and in maintaining a substantially constant differential in pressure at the point of constriction.

6. An apparatus of the class described comprising a conduit, a-damper in the.con-

d'uit regulating the flow of gas therethrough, and means for maintaining a substantially constant differential in pressure at the damper whereby the quantity of gas flowing past the damper is in direct proportion to the damper opening alone.

-- Signed at New York city, in the county of New York, and State of New York, this 18th day of June, A. D 1925.

GEORGE H. GIBSON. 

